The present invention relates to a transmissive screen for receiving a display image enlarged and projected from display elements, and to a rear projection type image display apparatus (hereinafter referred to simply as a PTV) using the transmissive screen.
As is well known, a transmissive screen for a PTV includes a light diffusion layer(s) in which a granular light diffusion material is spread in order to increase the viewing angles in the horizontal and vertical directions. PTVs using as their display elements a fixed pixel device, such as a liquid crystal panel or a micro-mirror panel, employ a projection lens having a small projection pupil size, which causes a scintillation disturbance (also referred to as a speckle disturbance) or “hot bars” to occur. A scintillation disturbance is a “flicker” produced due to interference between the light diffusion material within the light diffusion layer and the light, while “hot bars” refers to light strips appearing in the direction in which the lenticular lenses are arranged. Configurations for reducing the occurrence of these phenomena are described in Japanese Patent Laid-Open Publication No. 2002-236319 (hereinafter referred to as Patent Document 1) and Japanese Patent Laid-Open Publication No. 10-301208 (1998) (hereinafter referred to as Patent Document 2).
The configuration for reducing the above scintillation disturbance or “hot bars” disclosed in FIG. 1 of Patent Document 1 is such that: a light diffusion layer is provided on a Fresnel lens sheet having a Fresnel lens formed on its light exit surface; as a front sheet, a transparent resin substrate is disposed on the light exit side of a lenticular lens sheet having lenticular lenses on its light incident side; and two or more light diffusion layers each having a light diffusion material therein at a different dispersion density are laminated on the light exit side of the transparent resin substrate. The configuration disclosed in FIG. 1 of Patent Document 2, on the other hand, is such that two light diffusion layers are each laminated on a respective one of the light incident and light exit sides of a resin layer (acting as the front sheet) disposed on the light exit side of a lenticular lens sheet.